Temporary bipolar heart wire

ABSTRACT

The present invention includes within its scope a temporary lead for pacing, sensing, monitoring, or defibrillating at least a portion of a human or animal organ, and methods for implanting and making same. The lead has at least two electrodes and distal and proximal ends, and a novel weakened zone disposed between the blunt end of a needle and at least two electrical connectors attached to the proximal end of the lead body. The novel weakened zone permits the needle to be separated from the connectors by application of a sufficiently large bending moment or pulling force thereto. Following separation of the connectors from the needle, the connectors may be attached directly and quickly to an external electrical apparatus.

FIELD OF THE INVENTION

The present invention relates generally to heart wires and leads, andmore particularly to temporary bipolar heart wires and leads for pacing,defibrillating and monitoring.

BACKGROUND OF THE INVENTION

Unipolar and bipolar surgically implanted temporary heart wires are wellknown in the art, some examples of which may be found in the issued U.S.Patents listed in Table 1 below.

                  TABLE 1                                                         ______________________________________                                        Prior Art Patents                                                             U.S Pat. No.                                                                              Title                                                             ______________________________________                                        3,035,583   Conductive Sutures                                                3,125,095   Flexible Stainless Steel Sutures                                  3,664,347   Electric Heart Stimulation Method and                                         Electrode                                                         3,949,756   Sutures with Notch Near Needle-Suture                                         Junction                                                          4,010,756   Heart Pacer Lead Wire with Break-                                             Away Needle                                                       B1 4,010,756                                                                              Heart Pacer Lead Wire with Break-                                             Away Needle                                                       4,054,144   Short-Crimp Surgical Needle                                       4,338,947   Positive Fixation Heart Wire                                      4,341,226   Temporary Lead with Insertion Tool                                4,442,840   Electrical Connector Apparatus and                                            Method for a Temporary Cardiac Pacing                                         Wire                                                              4,444,207   Method of Anchoring a Temporary Cardiac                                       Pacing Lead                                                       4,530,368   Temporary Bipolar Pacing Lead                                     4,541,440   Bipolar Epicardial Temporary Pacing Lead                          4,553,554   Electrical Lead and Method for Temporary                                      Cardiac Pacing                                                    4,630,617   Heart Pacer Lead Wire with Pull-Away Needle                       4,633,880   Surgical Electrode                                                4,693,258   Surgical Electrode for Cardiac Pacing and                                     Monitoring                                                        4,972,833   Epicardiac Pacing Lead                                            5,217,027   Temporary Cardiac Lead                                            5,241,957   Bipolar Temporary Pacing Lead and                                             Connector and Permanent Bipolar Nerve Wire                        5,314,463   Bipolar Nerve Electrode                                           5,350,419   Cardiac Pacing Lead                                               5,423,876   Intramuscular Lead Having Improved Insertion                      ______________________________________                                    

All patents listed in Table 1 hereinabove are hereby incorporated byreference herein in their respective entireties. As those of ordinaryskill in the art will appreciate readily upon reading the Summary of theInvention, Detailed Description of the Preferred Embodiments and Claimsset forth below, many of the devices and methods disclosed in thepatents of Table 1 may be modified advantageously by using the teachingsof the present invention.

Surgically implanted temporary heart wires for use as heart pacer andmonitoring electrodes are well known in the medical profession. Ingeneral, such a heart wire is constructed of a number of fine, stainlesssteel wires twisted together to form a single, flexible, multifilamentelectrode wire. The major portion of the wire is typically insulatedwith a polyethylene, polytetrafluoroethylene, silicone, nylon, or othersuitable electrically nonconductive and biocompatible materials, with ashort length of wire at either end left uninsulated.

To one uninsulated end of such an electrode wire there is generallyattached by swaging or other means a fine curved needle for piercing theheart tissue to place the uninsulated end of the electrode in themyocardium or epicardium. At the other end of such an electrode wirethere is generally affixed a Keith-type cutting needle for piercing thethoracic wall to lead the electrode to an outer point for connectionwith the pacemaker. Once the electrode has been properly positioned, thecurved needle and the Keith-type needle are typically clipped off andthe uninsulated end of the electrode is ready for attachment to apacemaker or monitoring device.

Some prior art unipolar heart wires have break-away Keith-type needlesattached to their proximal ends, where no clipping is required to removethe needle from the heart wire. Other prior-art Keith-type break-awayneedles require the use of, or most preferably employ, an externaladapter or transition box for breaking the needle in the appropriatelocation and facilitating attachment of electrical conductors in thelead to an external electrical apparatus. See, for example, the bipolarheart wire and corresponding external connector disclosed in U.S. Pat.No. 5,241,957, where the external connector is required to establishelectrical connection between an EPG or PSA and the heart wire.

Many known heart wires are characterized in having one of the twofollowing disadvantages. First, when some known unipolar heart wires areused in applications requiring two electrodes, two different, separateheart wires must be attached to the heart in two separate procedures.Attaching two such heart wires consumes valuable time at a criticalstage in heart surgery. Second, when some known bipolar heart wires areused, the needle attached to the proximal end of the heart wire forpiercing the transthoracic wall must be clipped off with a scissors orother tool, and pin connectors must be attached to the resulting bareseparate wires for establishing electrical connection to an externalpacemaker or external electrical apparatus. These steps of needleremoval and wire attachment are separate, time consuming acts, and alsooccur at a critical stage in heart surgery. Moreover, upon repeatedattachment, removal and reattachment, the ends of the stainless steelwire may fray and become difficult to work with.

What is needed is a heart wire that attaches easily and quickly to theheart but which also has convenient, easy-to-use connectors disposedbetween the proximal end of the heart wire and an external pulsegenerator (EPG), pacing system analyzer (PSA), defibrillator or othersuch external electrical apparatus. Most preferably, the heart wireshould not require substantial electrical or mechanical manipulations bythe surgeon, should be comfortable to the patient, and should establishsecure and reliable electrical contacts. Finally, the heart wire shouldbe reasonably economical to manufacture.

Summary of the Invention

The present invention has certain objects. That is, the presentinvention provides solutions to problems existing in the prior art. Itis an object of the present invention to provide a surgical electrodehaving a needle, the sharpened proximal end of which can be removedwithout cutting. It is a further object of this invention to provide asurgical electrode which is quickly and easily attached to an externalelectrical apparatus after the sharpened end of the needle has beenremoved. It is yet a further object of this invention to providesurgical electrodes having electrical connecting means adapted forspecific electrical devices.

The present invention has certain advantages. More particularly, theheart wire of the present invention: (a) reduces patient trauma; (b)reduces the number of puncture sites in the myocardium or epicardium;(c) reduces the number of puncture sites in the thorax; (d) is easy touse; (e) permits two electrodes to be implanted quickly during acritical stage of heart surgery; (f) has electrodes spaced apredetermined optimal distance apart for sensing and pacingapplications; (g) attaches to external pacemakers, defibrillators,monitoring equipment and other external electrical apparatus quickly,easily, securely and reliably; (h) does not require lead wires to beclipped with scissors; (i) requires no use of an external, separateadapter or transition box for separating or breaking the needle from theconnectors; (j) requires no use of an external, separate adapter ortransition box for establishing electrical connection between theelectrodes and an external electrical apparatus; (k) prevents the distalends of electrode wires from becoming frayed; (l) has fewer parts thanmany prior art heart needles; (m) is less expensive to manufacture; (n)helps reduce health care costs, and (o) increases patient safety owingto shortened implantation times and quicker connection to externalpacing, defibrillating or monitoring equipment.

The heart wire and needle of the present invention have certainfeatures, including one or more of the following: (a) a chest needlehaving a pointed or proximal end and a blunt or distal end, the bluntend being breakingly, snappingly, crimpingly, compressionally,slidingly, elastically, gluingly, viscously, vacuumingly or otherwiseattached separably to the proximal ends of at least two connectors; (b)at least two connectors that upon being separated from the blunt end ofthe needle form pins or other structures suitable for fitting in orotherwise appropriately engaging an external connector configured toreceive the connectors, where the external connector is attached to anexternal electrical apparatus for monitoring, pacing or defibrillatingthe heart; (c) a curved, straight or otherwise shaped needle disposed atthe distal end of the heart wire that is suitable for piercing themyocardium or epicardium, and (d) two or more electrodes located betweenthe distal and proximal ends of the heart wire for pacing,defibrillating or monitoring the heart.

In one preferred embodiment, the present invention is a temporarybipolar lead having a proximal and a distal end, and comprises a chestneedle at its proximal end, the needle having a proximal pointed end anda distal blunt end attached to at least two connectors by a weakenedzone, at least two pacing, sensing or defibrillating electrodes disposednear the distal end, a coil affixation member, and a curved needle, thecurved needle being attached to the distal end of the lead, the coilaffixation member being disposed between the distal end and the proximalend. At least two electrical conductors extend between the electrodesand the connectors.

Other objects, features, advantages and embodiments of the presentinvention will become apparent upon reading the detailed description andthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a preferred embodiment of the presentinvention;

FIG. 2 s a side view of the lead of FIG. 1;

FIG. 3 shows a perspective view of the proximal end of a preferredembodiment present invention;

FIG. 4 perspective view of a preferred method of manually applying forceto a preferred embodiment of the present invention to cause theconnectors to seperate from the blunt end;

FIG. 5(a) shows a perspective view of a first preferred embodiment ofthe chest needle of the present invention;

FIG. 5(b) shows an enlarged view of the distal end of the chest needleof FIG. 5(a);

FIG. 5(c) shows an enlarged view of the connectors of FIG. 5(a) prior tothe distal ends thereof being inserted in the blunt end of the needle;

FIG. 5(d) shows an enlarged cross-sectional view of the weakened zone ofthe chest needle of FIG. 5(a);

FIG. 6(a) shows a perspective view of a second preferred embodiment ofthe chest needle of the present invention;

FIG. 6(b) shows an enlarged view of the distal end of the chest needleof FIG. 6(a);

FIG. 6(c) shows an enlarged view of the connectors of FIG. 6(a) prior tothe distal ends thereof being inserted in the blunt end of the needle;

FIG. 6(d) shows an enlarged cross-sectional view of the weakened zone ofthe Nest needle of FIG. 6(a);

FIG. 7(a) shows a perspective view of a third preferred embodiment ofthe chest needle of the present invention;

FIG. 7(b) shows an enlarged view of the distal end of the chest needleof FIG. 7(a);

FIG. 7(c) shows a side view of the chest needle of FIG. 7(a);

FIG. 7(d) shows an enlarged cross-sectional view of the weakened zone ofthe chest needle of FIG. 7(a);

FIG. 8 shows a perspective view of a fourth preferred embodiment of thechest needle of the present invention;

FIG. 9 shows an enlarged cross-sectional view of a portion of the distalend of a preferred embodiment of the present invention;

FIG. 10 shows an enlarged side view of a portion of the proximal end ofa preferred embodiment of the present invention;

FIG. 11 shows an enlarged cross-sectional view of a portion of theproximal end of a preferred embodiment of the present invention;

FIG. 12 shows an enlarged cross-sectional and side view of a portion ofthe proximal end of a preferred embodiment of the present invention;

FIG. 13 shows an enlarged side view of a preferred embodiment of theweakened zone of the present invention;

FIG. 14 shows a curved needle in a preferred embodiment of the presentinvention being inserted into the ventricular myocardium;

FIG. 15 shows a preferred embodiment of the present invention where bothelectrodes are positioned within the ventricular myocardium;

FIG. 16 shows a preferred embodiment of the present invention where thecurved needle has pierced the atrial myocardium twice, and

FIG. 17 shows removal of the curved needle from a heart wire of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the figures and the detailed description, like numbers refer to likeelements, components and parts throughout.

As used in the specification and claims hereof, the following terms havethe particular meanings and definitions set forth below.

The terms "temporary heart wire," "temporary heart lead" and anysubstantially similar variants thereof mean a temporary heart lead orwire introduced surgically through the myocardium or epicardium from theexterior of the heart, where the lead or wire has at least one electrodenear its distal end for monitoring, pacing or defibrillating the heartat or near a myocardial or epicardial site, and where the lead or wirehas at least one connector or needle near its proximal end forelectrical connection to an external pacing, monitoring, ordefibrillating apparatus." The terms "heart wire," "heart lead" and anysubstantially similar variants thereof are synonymous.

The term "proximal" means that portion of an apparatus, or component orelement of an apparatus, disposed in closer proximity to the end of thewire remaining outside a patient's body following the lead implantationprocedure than it is to the end of the wire implanted in or attached tothe heart.

The term "distal" means that portion of an apparatus, or component orelement of an apparatus, disposed in closer proximity to the end of thewire that is inserted through or attached first to the myocardium orepicardium during a wire implantation procedure than it is to the end ofthe wire that remains outside the patient's body following the leadimplantation procedure. The term "chest needle" or "needle" means theproximal end of the heart wire of the present invention, and includesthe pointed end of the needle, and the shank and body thereof, or maymean the needle disposed at the distal end of the lead of the presentinvention, a piercing means, or a means for piercing, depending on theparticular context in which the term "needle," "piercing means," or"means for piercing" appears. Additionally, needle 120 may include theweakened zone of the needle intermediate between the blunt end of theneedle and the connectors, and may also include the connectors attachedto the weakened zone or the blunt end.

The term "blunt" means the shank of the needle and that portion of thechest needle disposed proximally of the connectors and in proximitythereto. The blunt portion of the needle may include further thatportion of the needle connected directly to the proximal ends of theconnectors.

FIG. 1 shows a perspective view of a preferred embodiment of the presentinvention designed specifically for pacing and sensing applications.Heart lead or wire 10 has distal end 20 and proximal end 30, and mostpreferably comprises needle 120, connectors 150 and 160, weakened zone170, coaxial conductor or lead body 70, proximal electrode 50, distalelectrode 40, coil affixation member 60, strand 180 and curvedatraumatic needle 190.

Strand 180, preferably formed of polypropylene and constituting amonofilament, forms coil affixation member 60, attaches to distalelectrode 40 and extends to atraumatic curved needle 190. Coilaffixation member 60 may be similar to the type of coil disclosed inU.S. Pat. No. 4,341,226. Coil 60 ensures secure temporary fixation ofwire 10 in the heart and prevents dislodgments which might otherwiseoccur were a smooth tipped lead employed. Most preferably, one length ofpolypropylene comprises coil 60 and strand 180. More than one curvedneedle 190 may be attached to distal end 20 of lead 10. For example,each conductor of lead body 70 may terminate in a separate curvedneedle.

Lead body 70 may comprise any pair of suitable flexible electricalconductors, such as coaxial conductors or so-called "lamp cord" or"zip-cord" (e.g., side-by-side) conductors. Most preferably, lead body70 is a coaxial pair of inner and outer electrical conductors, where theconductors are formed of helically wound strands of multifilament ortwisted stainless steel. Lead body 70 most preferably comprisesconductors that provide a high degree of flexibility and superiormechanical and electrical properties.

Electrodes 40 and 50 are preferably formed of medical grade stainlesssteel suitable for temporary applications, and are preferably spaced apredetermined distance apart known to optimize the delivery of pacingpulses or the detection and sensing of cardiac electrical signals.Distal electrode 40 is mechanically and electrically connected by innerconductor 80 (not shown in FIG. 1 but shown in FIGS. 9, 11 and 12) tofirst connector 150 at the proximal end of lead 10, which, in turn, ismechanically connected to blunt end 140 of needle 120 by weakened zone170. Proximal electrode 50 is mechanically and electrically connected byouter conductor 90 (not shown in FIG. 1 but shown in FIGS. 9, 11 and 12)to second connector 160 at the proximal end of lead 10, which is also,in turn, mechanically connected to blunt end 140 of needle 120 byweakened zone 170.

Needle 120, most preferably of the atraumatic type, is a chest needlefor piercing the thorax, and has pointed end 130 and blunt end 140.Needle 120 is preferably substantially straight between pointed end 130and blunt end 140. Pointed end 130 has a cutting edge designed forpiercing the thoracic wall of the patient. Blunt end 140 attachesbreakingly, snappingly, crimpingly, compressionally, adhesively,gluingly, elastically, slidingly or in otherwise suitable connecting yetseparable fashion to the proximal ends of connectors 150 and 160.Weakened or pull-apart zone 170 separates the proximal ends ofconnectors 150 and 160 from blunt end 140. Connectors 150 and 160 mostpreferably form cylindrically shaped pin connectors having circularcross-sections upon being separated from blunt end 140. Other structuralconfigurations of connectors 150 and 160 fall within the scope of thepresent invention and include, but are not limited to, pin-shapedconnectors having rectangular or square cross-sections, reed-shapedconnectors, and flexible connectors.

Lead 10 includes curved needle 190 for piercing the myocardium orepicardium preparatory to drawing the heart wire 10 and its electrodeswithin the myocardium or epicardium. The proximal end of curved needle190 is connected to strand 180.

FIG. 2 shows a side view of the lead of FIG. 1. Note that coil 60 isshown in FIG. 1, but is not shown in FIG. 2. Coil 60 is an optionalcomponent of the present invention, and is not required for the practicethereof. For example, the distal end of lead 10 may be secured to themyocardium or epicardium with sutures instead of coil 60.

FIG. 3 shows a perspective view of the proximal end of a preferredembodiment of lead 10. After the surgeon attaches the distal end of lead10 to the myocardium or epicardium using curved needle 190 and somemeans for securing the electrodes thereto such as coil 60, needle 120pierces the patient's thorax and is brought outside the patient's chest.

When the electrodes have been positioned suitably in the myocardium orepicardium and lead 10 is ready for attachment to an external electricalapparatus such as an EPG, needle 120 is snapped at weakened zone 170 asshown in FIG. 4 by applying a bending moment about zone 170. FIG. 4shows a perspective view of a preferred method of applying forcemanually to a preferred embodiment of lead 10 to cause the weakened zoneto fail structurally, and to thereby separate the connectors 150 and 160from blunt end 140. The snapped off portion of the needle is discardedwhile connectors 150 and 160 are readily inserted into a properly sizedreceptacle in the EPG or other external electrical apparatus. Connectors150 and 160 are structures having standardized dimensions, and areconfigured to permit attachment, removal, and reattachment to anexternal electrical apparatus in quick, ready, reliable, secure and safefashion as required, and without encountering frayed ends characteristicof bare, multifilament stainless steel wires.

The present invention permits reliable and secure electrical connectionsto be established securely, reliably, quickly and safely between atleast two electrodes and the external electrical apparatus without theuse of a separate connector housing such as that disclosed in U.S. Pat.No. 5,241,947. A separate connector housing adds extra cost to heartwire system. A separate connector housing also increases the likelihoodof electrical connection failures occurring between lead 10 and theexternal electrical apparatus to which lead 10 is connected because thehousing contains additional electrical junctions and points ofconnection not present in the invention. Additionally, a housing likethat disclosed in the foregoing '947 patent increases the complexity of,and time required to complete, a heart wire implant procedure. Thus, thepresent invention may simplify implant procedures, reduce the amount oftime required to complete such procedures, and increase the reliabilityand safety of the heart wire system respecting prior art heart wiresystems.

FIGS. 5(a) through 5(d) show different views of a first preferredembodiment of chest needle 120 of the present invention. Reduceddiameter pins 151 and 161 are integral to electrically conductive,stainless steel, cylindrically-shaped pin connectors 150 and 160, andextend from the proximal ends thereof. Regions 156 and 166 are scoredmechanically, and are disposed between pins 151 and 161 and the proximalends of connectors 150 and 160. Scoring provides the user with a meansof visually identifying the region where the connectors will break.After pins 151 and 161 are fitted into corresponding recesses 153 and163 disposed within blunt end 140, pins 151 and 161 are swaged orpreferably crimped in place by at least one crimp 172, and morepreferably by two crimps disposed on opposing sides of needle 120.

The proximal ends of conductors 80 and 90 (not shown in FIGS. 5(a)through 5(d)) slide within recesses 155 and 165 and are crimped inplace, thus establishing electrical and mechanical connections betweenthe conductors and the connectors.

Weakened zone 170 preferably comprises the proximal ends of connectors150 and 160, scored regions 156 and 166, blunt end 140, pins 151 and 161and recesses 153 and 163. Connectors 150 and 160 separate from needle120 at scored regions 156 and 166 when a bending moment is applied toweakened zone 170.

Weakened zone 170 may be formed by methods other than scoring. Forexample, zone 170 may be formed by machining, forming a groove byrotating the connectors or needle in contact with a cutting wheel, or bycutting a notch or forming a crimp on one or both sides of theconnectors or the needle. A groove machined or scored in connectors 150and 160 or pins 151 and 161 reduces the diameter of needle 120 andtherefore reduces the strength of needle 120 in weakened zone 170.

Weakened zone 170 may be formed in ways that do not require connectors150 and 160 to break in certain regions. For example, the amount offorce applied when forming crimp 172 may be adjusted so that connectors150 and 160 may be pulled out of blunt end 140 manually or when aspecial removal tool is used. Alternatively, pins 151 and 161 may havediameters sized to frictionally engage the inner sidewalls of recesses155 and 165 with sufficient force to prevent their removal therefromuntil a predetermined amount of outward force is applied to pullconnectors 150 and 160 from blunt end 140.

Less preferably, weakened zone 170 may be formed by gluing or bindingpins 151 and 161 in recesses 153 and 163 using a suitable biocompatibleadhesive or viscous material so that a user may pull connectors 150 and160 out of blunt end 140 when a sufficiently large predetermined forceis applied thereto.

Weakened zone 170 may also be obtained by modification of crystallinestructure through heat treating by drawing the needle to create a neckeddown segment, annealing weakened zone 170, or by any other convenient orsuitable means.

Grooved or otherwise weakened zone 170 of needle 120 may be located atany convenient distance from blunt end 140. The lengths of theconnectors remaining after the pointed end is snapped off should besufficient for grasping and inserting the connectors into an electricalreceptacle. In general, weakened zone 170 is preferably at least 1centimeter from the distal ends of the connectors or the pointed end 130of needle 120. Most preferably this distance is between about 2 and 3centimeters. When the distance between weakened zone 170 and pointed end130 is less than about 1 centimeter, it becomes difficult to graspneedle 120 for breaking. When connectors 150 and 160 are less than 1centimeter long, it becomes difficult to handle and insert theconnectors into electrical receptacles.

Needle 120 may be curved, straight, or of any other desired, suitableconfiguration. Pointed end 130 may have any desired cross-sectionalconfiguration. While a triangular cross-section is generally preferred,pointed end 130 may also be circular, triangular, rectangular, square orany other suitable shape in cross-section. Connectors 150 and 160 mayalso be circular, triangular, rectangular, square or any other suitableshape in cross-section. Such connector cross-sections may findparticular use where the connectors are intended to be connected to aparticular external electrical apparatus and no other.

Since connectors 150 and 160 establish electrical connection with anexternal electrical apparatus, insulation 100 and 110 (not shown inFIGS. 5(a) through 5(d) may extend up to or even over the distal ends ofconnectors 150 and 160. Abutting the insulation to a location near bluntend 140 and heat shrinking and sealing the joint may provide theadvantage of a smooth, continuous and sealed exterior surface thatfacilitates threading needle 120 through the thoracic wall. In someconnectors of the prior art, it has been necessary to provide a segmentof uninsulated wire or connector adjacent the needle to allow forelectrical connection to an external electrical apparatus after theneedle has been clipped off the wire, or to take an extra step ofstripping insulation from the wire to provide an electrical connection.

FIGS. 6(a) through 6(d) show different views of a second preferredembodiment of the chest needle of the present invention. Pins 151 and161 are integral to electrically conductive, stainless steel,cylindrically-shaped pin connectors 150 and 160, and extend from theproximal ends thereof Regions 156 and 166 are scored mechanically. Bluntend 140 is preferably compressed slightly in the vicinity of axialrecess 157 and in a vertical direction to increase the horizontaldimension of axial recess 157 to ease the insertion of pins 151 and 161therein. Following insertion of pins 151 and 161 in recess 157, bluntend 140 is crimped to form at least one crimp 172, and more preferablytwo crimps disposed on opposing sides of needle 120.

The proximal ends of conductors 80 and 90 (not shown in FIGS. 6(a)through 6(d)) slide within recesses 155 and 165 and are crimped in placeat crimps 154 and 164 (shown in FIG. 12), thus establishing electricaland mechanical connections between the conductors and the connectors.

Weakened zone 170 preferably comprises the proximal ends of connectors150 and 160, scored regions 156 and 166, blunt end 140, pins 151 and 161and axial recess 157. Connectors 150 and 160 separate from needle 120 atscored regions 156 and 166 when a bending moment is applied to weakenedzone 170.

Weakened zone 170 may be formed in ways that do not require connectors150 and 160 to break in certain regions. For example, the amount offorce applied when forming crimp 172 may be adjusted so that connectors150 and 160 may be pulled out of blunt end 140 manually or when aspecial removal tool is used. Alternatively, pins 151 and 161 may havediameters sized to frictionally engage the inner sidewall of axialrecess 157 with sufficient force to prevent their removal therefromuntil a predetermined amount of outward force is applied to pullconnectors 150 and 160 from blunt end 140.

FIGS. 7(a) through 7(d) show different views of a third preferredembodiment of the chest needle of the present invention. Connectors 150and 160 are integral to and form the distal portion of electricallyconductive, stainless steel needle 120. Notches 159 are machined in thetop and bottom surfaces of connectors 150 and 160 to form weakened zone170. Less preferably, weakened zone 170 consists of only one notch 159.The proximal ends of conductors 80 and 90 (not shown in FIGS. 7(a)through 7(d)) slide within recesses 155 and 165 and are preferablycrimped in place, thus establishing electrical and mechanicalconnections between the conductors and the connectors. Connectors 150and 160 separate from needle 120 at notches 159 when a bending moment isapplied to weakened zone 170.

FIG. 8 shows a perspective view of a fourth preferred embodiment of thechest needle of the present invention. Needle 120 and connectors 150 and160 are machined, forged or otherwise formed of a single piece ofstainless steel. Longitudinal groove 158 separates conductor 150 fromconductor 160 along their respective entire lengths except near theintersection of blunt end 140, circumferential groove 167 andlongitudinal groove 158, where conductors 150 and 160 are attached toblunt end 140 by a zone of reduced diameter stainless steel. Connectors150 and 160 separate from needle 120 at circumferential groove 167 whena bending moment is applied to weakened zone 170.

FIG. 9 shows an enlarged cross-sectional view of the distal end of oneembodiment of the present invention, where lead 10 is designedspecifically for pacing and sensing applications. FIG. 9 showsaffixation coil 60 and electrodes 40 and 50 in greater detail.Affixation coil 60 preferably includes ten right hand wound turns and iscrimpingly affixed to tip electrode 40. Inner conductor 80 is covered byinner insulation 100. Electrode 50 is crimpingly affixed to outerconductor 90 which is covered by outer insulation 110.

The two conductors of coaxial wire 70 preferably comprise twisted andhelically wound strands of medical grade stainless steel wire. Lesspreferably those conductors may be formed of single strands of stainlesssteel, or of one or more strands of electrically conductive polymericmaterial. Inner insulation 100 is most preferably formed of fluorinatedethylene propylene (FEP), polytetrafluorethylene (PTFE), or any othersuitable medical grade, biocompatible dielectric insulating coating suchco-polymer polytetrafluorethylene, polyethylene, silastic, neoprene,polypropylene, or polyurethane. Inner insulation 100 covers andinsulates inner conductor 80, which is preferably composed of 19twisted, wound, or twisted and wound stainless steel filaments orstrands.

Outer conductor 90 is preferably composed of 26 to 40 medical gradestainless steel strands or filaments, and most preferably 32 suchstrands, wound in helical fashion over inner insulation 80. Helicalwinding of the outer conductors imparts a high degree of flexibility tolead 10. Inner electrical insulation 100, disposed between the inner andouter electrical conductors, may be. Outer electrical insulation 110 ispreferably formed of FEP or polyethylene, or any other suitablebiocompatible material such as medical grade, biocompatible PTFE,polyethylene, silastic, neoprene, polypropylene, or polyurethane.

FIG. 10 shows an enlarged side view of a portion of the proximal end ofa lead of the present invention, where two conductors and theircorresponding layers of insulation are separated from one another atjunction 200, most preferably formed of heat shrink tubing.

FIG. 11 shows an enlarged cross-sectional view of junction 200, wherecoaxial conductor 70 is separated into two separate wires 174 and 176.First wire 174 comprises inner conductor 80 and inner insulation 100.Second wire 176 comprises outer conductor 90 and outer insulation layer110.

At a distance proximal from junction 200 wires 174 and 176 are connectedelectrically and mechanically to connectors 150 and 160. As shown inFIG. 12, this is most preferably accomplished by stripping anappropriate length of overlying insulation away from the proximal endsof wires 174 and 176, compressing distal ends 152 and 162 of connectors150 and 160 along vertical axes, inserting the bare wire ends intorecesses 155 and 165, and crimping the wires in place to form crimps 154and 164.

FIG. 13 shows an enlarged side view of a preferred embodiment ofweakened zone 170 of the present invention. Weakened zone 170 is shownbeing disposed between connectors 150 and 160 and needle 120. Crimp 172compressionally holds pins 151 and 161 in blunt end 140 of needle 120.

The procedure for implanting lead 10 in the heart may be outlinedbriefly as follows. Fine curved needle 190 at distal end 20 of lead 10is passed through the ventricular myocardium or epicardium. Affixationcoil 60 and electrodes 40 and 50 are pulled through the heart tissuepenetrated by needle 190 until the electrodes are located suitablywithin the myocardium or epicardium, and affixation coil 60 anchorselectrodes 40 and 50 to the heart. Needle 190 and the portion ofmonofilament 180 extending from the heart are clipped off with ascissors, leaving the remainder of lead 10 extending from the heart.Chest needle 120 then pierces the patient's thorax, and is broken atweakened zone 170 to permit connectors 150 and 160 to be connected to anexternal sensing, monitoring, pacing or defibrillating device. When itis time to remove the lead, the surgeon simply carefully pulls the leadand withdraws it from the patient's heart and chest. Affixation coil 60is flexible enough to allow the heart wire to be gently pulled from themyocardium or epicardium without damaging the myocardium.

FIG. 14 shows curved needle 190 in a preferred embodiment of the presentinvention being inserted through epicardium 230 of ventricle 220 andinto myocardium 240 of heart 210 preparatory to drawing bipolar lead 10into myocardium 240 or epicardium 230.

FIG. 15 shows a preferred embodiment of the present invention whereelectrodes 40 and 50 are positioned within ventricle 220 in myocardium240 or epicardium 230. Affixation coil 60 prevents distal end 20 of lead10 from

FIG. 16 shows lead 10 positioned within myocardium 240 and epicardium230 of atrium 250, where affixation coil 60 and electrodes 40 and 50 arepositioned within myocardium 240 or epicardium 230. For atrialimplantations the positioning of lead 10 shown in FIG. 16 may bepreferred, where the surgeon pierces the atrium twice with curved needle190, and a portion of lead 10 is positioned above heart 210. The leadpositioning shown in FIG. 16 may be preferred as a means of preventingaccidental penetration of the myocardium since the wall of atrium 250 ismuch thinner than that of ventricle 220.

FIG. 17 shows the step in the implantation procedure where the surgeoncuts strand 180 at the exterior surface of the heart wall, leavingaffixation coil 60 and electrodes 40 and 50 embedded in myocardium 240or epicardium 230.

Although only a few exemplary embodiments of the present invention havebeen described in detail above, those skilled in the art will appreciatereadily that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of the invention. Accordingly, all such modifications areintended to be included within the scope of the present invention asdefined in the following claims.

For example, the Figures show Keith-type needles, but any needle havingsuitably shaped and configured pointed and blunt ends and a suitableshank portion may be used. The needle need not be formed of stainlesssteel or an electrically conductive material, but may be formed ofmedical grade plastic, polymers or any other suitable material.Moreover, there is no requirement that the needle of the presentinvention be straight, substantially straight or solid in cross-section.Indeed, the needle of the present invention may be curved or hollow.Finally, the needle of the present invention need not have a pointed endbecause in some cases the needle may be withdrawn from a patient's bodythrough an existing natural or surgically made orifice, hole or opening.

Since the connectors of the present invention are required to be inelectrical contact with the conductors, the conductors are preferablyattached to the distal ends of the connectors by a combination ofcompressing, inserting and crimping steps. Other methods of electricallyconductive attachment such as brazing, soldering or welding may ofcourse be utilized. The connectors of the present invention are notlimited to pin connectors, but include any plurality of connectorshaving suitable configurations for attachment to the blunt end. Theproximal ends of the connectors need not be removed from the needle bymanual means only. Specially configured tools may be used to break orpull the connectors free of the needle.

The present invention is not limited to embodiments where the weakenedzone breaks upon the application of sufficient bending moment thereto,or where the proximal ends of the connectors attach directly to theblunt end. The weakened zone may be formed of connectors whose distalends attach gluingly, vaccuumingly, elastically or otherwise to theblunt end, or whose distal ends pull out of the blunt end uponsufficient pulling force being applied thereto. The weakened zone mayfurther comprise an intermediate member disposed between the proximalends of the connectors and the blunt end that may not be electricallyconductive. For example, an intermediate member might be formed ofplastic and be configured to break upon the application of anappropriate bending moment. The resulting separated connectors wouldthen have non-conductive plastic portions disposed on their proximalends, but those portions would not preclude effective electrical andmechanical connection between the connectors and an external electricalapparatus. Alternatively, the weakened zone might be formed, at leastpartially, of medical grade heat shrink tubing.

Furthermore, the present invention is not limited to embodiments whereall electrodes are attached to the same lead body, where one electrodemust necessarily be disposed proximally or distally of the otherelectrode or electrodes, or where the electrodes are crimpingly attachedto the conductors. For example, an electrode of the present inventionmay be formed by merely stripping away insulation overlying bare wire ata suitable location, by attaching a clip to bare wire, or by heatshrinking electrically conductive heat shrink over selected portions ofbare wire. Nor is the present invention limited to embodiments where theelectrodes are introduced surgically with the aid of a curved needlethrough or into cardiac or other tissue. The present invention includeswithin its scope embodiments where the electrodes may be located on thesurface of the heart, inside the atrium or ventricle, or on or in theendocardium.

The scope of the present invention is not limited to pacing, monitoringor sensing applications, but extends to neural, defibrillation, cardiacmapping, abdominal stimulation, and other medical and medical deviceapplications and methods. The scope of the present invention is notlimited to applications where a human organ or plurality of organs issensed, monitored, paced, or defibrillated, but includes similarapplications in animals.

In the claims, means-plus-function clauses are intended to cover thestructures described herein as performing the recited function and notonly structural equivalents but also equivalent structures. Thus,although a nail and a screw may not be structural equivalents in that anail employs a cylindrical surface to secure wooden parts together,whereas a screw employs a helical surface, in the environment offastening wooden parts a nail and a screw are equivalent structures.

The present invention further includes within its scope methods ofimplanting, using and making the leads described hereinabove. Forexample, the invention includes a method for implanting a temporary leadhaving distal and proximal ends, the lead being suitable for pacing,sensing, monitoring, or defibrillating at least a portion of a human oranimal organ, the method comprising the steps of: (a) positioning atleast two electrodes in electrical contact with the portion of theorgan, the electrodes being electrically connected to first and secondelectrical conductors, respectively, the conductors having proximal endsconnected electrically to first and second connectors, respectively, theconnectors being configured for attachment to an external electricalapparatus; (b) securing the electrodes to the portion of the organ; and(c) separating the connectors from a blunt end of a chest needle havingdistal and proximal ends, the blunt end being disposed at the distal endof the needle, by application of a sufficiently large bending moment toa weakened zone disposed between the blunt end and the connectors. Theforegoing method may optionally include the steps of: (a) a firstpiercing step that precedes the positioning step, the first piercingstep comprising the step of piercing the organ with a pointed end of acurved needle, the curved needle being attached to the distal end of thelead, or (b) a second piercing preceding the separating step, the secondpiercing step comprising the step of piercing the thorax of a patientwith a pointed end of the chest needle, the pointed end being disposedat the proximal end of the chest needle, or (c) a connecting stepfollowing the separating step, the connecting step comprising the stepof electrically connecting the connectors to an external electricalapparatus. Alternatively, the separating step may be accomplished byapplication of a sufficiently large pulling force to the weakened zonesuch that the connectors are separated from the blunt end.

The present invention also includes within its scope a method for makinga temporary lead having distal and proximal ends, where the lead issuitable for pacing, sensing, monitoring, or defibrillating at least aportion of a human or animal organ. The method of making comprises thesteps of: (a) providing a lead body having distal and proximal ends andcomprising at least first and second electrical conductors havingproximal ends; (b) forming at least first and second electrodes, thefirst and second electrodes being electrically connected to the firstand second electrical conductors, respectively; (c) providing a needlehaving distal and proximal ends, the needle having a blunt end disposedat its distal end; (d) providing first and second connectors; (e)attaching the first and second connectors to the proximal ends of thefirst and second electrical conductors, respectively; (f) providing aweakened zone between the first and second electrical connectors and theblunt end, the connectors being separated from the blunt end byapplication of a sufficiently large bending moment to the weakened zone,the connectors being configured for attachment to an external electricalapparatus. Alternatively, the separating step may be accomplished byapplication of a sufficiently large pulling force to the weakened zone.

We claim:
 1. A temporary medical lead having distal and proximal ends,the lead being suitable for pacing, sensing, monitoring, ordefibrillating at least a portion of a human or animal organ,comprising:(a) a lead body having distal and proximal ends andcomprising at least first and second electrical conductors havingproximal ends, the first and second electrical conductors beingelectrically insulated from one another, and at least first and secondelectrodes attached, respectively, to the first and second electricalconductors, and (b) a substantially rigid needle assembly having distaland proximal ends, the needle assembly comprising: a first proximalportion comprising proximal and distal ends, the first portion having apointed end disposed at the proximal end thereof, a second distalportion comprising at least first and second connectors having distaland proximal ends, the distal ends of the connectors forming the distalend of the needle assembly, the first proximal portion and the seconddistal portion being substantially rigidly connected to one another, aweakened zone being disposed at least propinguant to the region disposedbetween the first proximal portion and the second distal portion, theneedle assembly, prior to the first and second portions thereof beingmanually separated from one another, forming a single contiguous andsubstantially rigid assembly, the first connector being attached to theproximal end of the first electrical conductor, the second connectorbeing attached to the proximal end of the second electricalconductor;wherein the connectors may be separated from the firstproximal portion by the application of a single sufficiently largebending moment to the weakened zone, the connectors being configured forattachment to an external electrical apparatus.
 2. The temporary lead ofclaim 1, wherein a strand having proximal and distal ends is attached tothe distal end of the lead body.
 3. The temporary lead of claim 2,wherein the strand is formed of polypropylene.
 4. The temporary lead ofclaim 2, wherein the strand is a monofilament.
 5. The temporary lead ofclaim 2, wherein the strand includes a coil affixation member.
 6. Thetemporary lead of claim 5, wherein the coil affixation member includesten right hand wound turns and is crimpingly affixed to one of the firstand second electrodes.
 7. The temporary lead of claim 2, wherein atleast one atraumatic needle is attached to the distal end of the strand.8. The temporary lead of claim 7, wherein the at least one atraumaticneedle is curved.
 9. The temporary lead of claim 1, wherein the distalends of the at least first and second electrical conductors terminate inseparate needles.
 10. The temporary lead of claim 1, wherein the firstand second conductors are formed of at least one of helically woundstrands of multifilament stainless steel, twisted strands ofmultifilament stainless steel, single strands of stainless steel, andstrands of electrically conductive polymeric material.
 11. The temporarylead of claim 1, wherein the at least first and second electricalconductors are inner and outer coaxial conductors, respectively.
 12. Thetemporary lead of claim 11, wherein a layer of inner insulationseparates and electrically insulates the first inner conductor from thesecond outer conductor, the inner insulation being formed from amaterial selected from the group consisting of fluorinated ethylenepropylene (FEP), polytetrafluorethylene (PTFE), co-polymerpolytetrafluorethylene, polyethylene, silastic, neoprene, polypropyleneand polyurethane.
 13. The temporary lead of claim 12, wherein the outerconductor is composed of between about 26 and 40 medical grade stainlesssteel strands or filaments wound helically over the layer of innerinsulation.
 14. The temporary lead of claim 11, wherein a layer of outerinsulation is disposed over the outer surface of the outer secondconductor, the outer insulation being electrically insulative and formedfrom a material selected from the group consisting of FEP, polyethylene,biocompatible PTFE, polyethylene, silastic, neoprene, polypropylene andpolyurethane.
 15. The temporary lead of claim 11, wherein the innerconductor is composed of about 19 medical grade twisted, wound, ortwisted and wound stainless steel filaments or strands .
 16. Thetemporary lead of claim 12, wherein the outer conductor is composed ofbetween about 26 and 40 medical grade stainless steel strands orfilaments wound helically over the inner insulation.
 17. The temporarylead of claim 1, wherein the at least first and second electricalconductors are zip cord conductors.
 18. The temporary lead of claim 1,wherein the at least first and second electrodes are formed of medicalgrade stainless steel.
 19. The temporary lead of claim 1, wherein thefirst electrode is a distal electrode, the first conductor forms aninner conductor, and the first electrode is mechanically andelectrically connected by the inner conductor to the first connector.20. The temporary lead of claim 1, wherein the second electrode is aproximal electrode, the second conductor forms an outer conductor, andthe second electrode is mechanically and electrically connected by theouter conductor to the second connector.
 21. The temporary lead of claim1, wherein the first proximal portion of the needle assembly forms anatraumatic needle.
 22. The temporary lead of claim 1, wherein the firstportion of the needle assembly is substantially straight.
 23. Thetemporary lead of claim 1, wherein the first portion of the needleassembly has a triangular cross-section.
 24. The temporary lead of claim1, wherein the first portion of the needle assembly is a Keith-typeneedle.
 25. The temporary lead of claim 1, wherein the first portion ofthe needle assembly is formed of medical grade plastic or polymer. 26.The temporary lead of claim 1, wherein the first portion of the needleassembly is curved.
 27. The temporary lead of claim 1, wherein thedistal end of the first portion of the needle assembly is attachedbreakingly, snappingly, crimpingly, compressionally, frictionally,adhesively, gluingly, or elastically to the proximal ends of the firstand second connectors.
 28. The temporary lead of claim 1, wherein thefirst and second connectors, upon being separated from the first portionof the needle assembly, form cylindrically-shaped pin connectors havingat least one of circular cross-sections, rectangular cross-sections andsquare cross-sections.
 29. The temporary lead of claim 1, wherein thefirst and second connectors form reed-shaped connectors.
 30. Thetemporary lead of claim 1, wherein the first and second connectors formflexible connectors.
 31. The temporary lead of claim 1, wherein thefirst and second connectors have reduced diameter pins disposed at theproximal ends thereof.
 32. The temporary lead of claim 31, wherein thefirst and second connectors each have a scored region disposed betweenthe reduced diameter pin and its proximal end.
 33. The temporary lead ofclaim 31, wherein the reduced diameter pins fit into correspondingindividual recesses disposed within the distal end of the first portionof the needle assembly.
 34. The temporary lead of claim 31, wherein thereduced diameter pins are frictionally engaged, adhered, glued, crimped,brazed, soldered or welded to the distal end of the first portion of theneedle assembly.
 35. The temporary lead of claim 1, wherein the proximalends of the first and second conductors slide within recesses disposedin the distal ends of the first and second connectors, the conductorsbeing crimped, brazed, soldered or welded in place therein to establishelectrical and mechanical connections between the conductors and theconnectors.
 36. The temporary lead of claim 1, wherein the weakened zoneis formed by crimping, scoring, machining or cutting a groove, a portionof a groove, or a notch on one or both sides of the connectors or theneedle.
 37. A temporary medical lead having distal and proximal ends,the lead being suitable for pacing, sensing, monitoring, ordefibrillating at least a portion of a human or animal organ,comprising:(a) a lead body having distal and proximal ends andcomprising at least first and second electrical conductors havingproximal ends, the first and second electrical conductors beingelectrically insulated from one another, and at least first and secondelectrodes attached, respectively, to the first and second electricalconductors, and (b) a substantially rigid needle assembly having distaland proximal ends, the needle assembly comprising: a first proximalportion comprising proximal and distal ends, the first portion having apointed end disposed at the proximal end thereof, a second distalportion comprising at least first and second connectors having distaland proximal ends, the distal ends of the connectors forming the distalend of the needle assembly, the first proximal portion and the seconddistal portion being substantially rigidly connected to one another, aweakened zone being disposed at least propinguant to the region disposedbetween the first proximal portion and the second distal portion, theneedle assembly, prior to the first and second portions thereof beingmanually separated from one another, forming a single contiguous andsubstantially rigid assembly, the first connector being attached to theproximal end of the first electrical conductor, the second connectorbeing attached to the proximal end of the second electricalconductor;wherein the connectors may be separated from the firstproximal portion by the application of a single sufficiently largepulling force to the weakened zone, the connectors being configured forattachment to an external electrical apparatus.
 38. The temporary leadof claim 37, wherein a strand having proximal and distal ends isattached to the distal end of the lead body.
 39. The temporary lead ofclaim 38, wherein the strand is formed of polypropylene.
 40. Thetemporary lead of claim 38, wherein the strand is a monofilament. 41.The temporary lead of claim 38, wherein the strand includes a coilaffixation member.
 42. The temporary lead of claim 41, wherein the coilaffixation member includes ten right hand wound turns and is crimpinglyaffixed to one of the first and second electrodes.
 43. The temporarylead of claim 38, wherein at least one atraumatic needle is attached tothe distal end of the strand.
 44. The temporary lead of claim 43,wherein the at least one atraumatic needle is curved.
 45. The temporarylead of claim 38, wherein the distal ends of the at least first andsecond electrical conductors terminate in separate needles.
 46. Thetemporary lead of claim 38, wherein the first and second conductors areformed of at least one of helically wound strands of multifilamentstainless steel, twisted strands of multifilament stainless steel,single strands of stainless steel, and strands of electricallyconductive polymeric material.
 47. The temporary lead of claim 38,wherein the at least first and second electrical conductors are innerand outer coaxial conductors, respectively.
 48. The temporary lead ofclaim 47, wherein a layer of inner insulation separates and electricallyinsulates the first inner conductor from the second outer conductor, theinner insulation being formed from a material selected from the groupconsisting of fluorinated ethylene propylene (FEP),polytetrafluorethylene (PTFE), co-polymer polytetrafluorethylene,polyethylene, silastic, neoprene, polypropylene and polyurethane. 49.The temporary lead of claim 48, wherein the outer conductor is composedof between about 26 and 40 medical grade stainless steel strands orfilaments wound helically over the layer of inner insulation.
 50. Thetemporary lead of claim 47, wherein a layer of outer insulation isdisposed over the outer surface of the outer second conductor, the outerinsulation being electrically insulative and formed from a materialselected from the group consisting of FEP, polyethylene, biocompatiblePTFE, polyethylene, silastic, neoprene, polypropylene and polyurethane.51. The temporary lead of claim 47, wherein the inner conductor iscomposed of about 19 medical grade twisted, wound, or twisted and woundstainless steel filaments or strands.
 52. The temporary lead of claim48, wherein the outer conductor is composed of between about 26 and 40medical grade stainless steel strands or filaments wound helically overthe inner insulation.
 53. The temporary lead of claim 37, wherein the atleast first and second electrical conductors are zip cord conductors.54. The temporary lead of claim 37, wherein the at least first andsecond electrodes are formed of medical grade stainless steel.
 55. Thetemporary lead of claim 37, wherein the first electrode is a distalelectrode, the first conductor forms an inner conductor, and the firstelectrode is mechanically and electrically connected by the innerconductor to the first connector.
 56. The temporary lead of claim 37,wherein the second electrode is a proximal electrode, the secondconductor forms an outer conductor, and the second electrode ismechanically and electrically connected by the outer conductor to thesecond connector.
 57. The temporary lead of claim 37, wherein the firstproximal portion of the needle assembly forms an atraumatic needle. 58.The temporary lead of claim 37, wherein the first proximal portion ofthe needle assembly is substantially straight.
 59. The temporary lead ofclaim 37, wherein the first proximal portion of the needle assembly hasa triangular cross-section.
 60. The temporary lead of claim 37, whereinthe first proximal portion of the needle assembly is a Keith-typeneedle.
 61. The temporary lead of claim 37, wherein the first proximalportion of the needle assembly is formed of medical grade plastic orpolymer.
 62. The temporary lead of claim 37, wherein the first proximalportion of the needle assembly is curved.
 63. The temporary lead ofclaim 37, wherein the distal end of the first proximal portion of theneedle assembly is attached crimpingly, compressionally, adhesively,gluingly, elastically, frictionally or slidingly to the proximal ends ofthe first and second connectors.
 64. The temporary lead of claim 37,wherein the first and second connectors, upon being separated from thedistal end of the first portion of the needle assembly, formcylindrically-shaped pin connectors having at least one of circularcross-sections, rectangular cross-sections and..
 65. The temporary leadof claim 37, wherein the first and second connectors form reed-shapedconnectors.
 66. The temporary lead of claim 37, wherein the first andsecond connectors form flexible connectors.
 67. The temporary lead ofclaim 37, wherein the first and second connectors each have a reduceddiameter pin disposed at its proximal end.
 68. The temporary lead ofclaim 67, wherein the reduced diameter pins fit into corresponding axialrecesses disposed within the distal end of the first portion of theneedle assembly.
 69. The temporary lead of claim 68, wherein theproximal ends of the connectors are frictionally engaged, adhered,glued, crimped, brazed, soldered or welded to the distal end of thefirst portion of the needle assembly.
 70. The temporary lead of claim37, wherein the first and second connectors have proximal ends that fitwithin corresponding axial recesses disposed within the distal end ofthe first portion of the needle assembly.
 71. The temporary lead ofclaim 70, wherein the proximal ends of the first and second connectorsare frictionally engaged, adhered, glued, crimped, brazed, soldered orwelded to the distal end of the first portion of the needle assembly.72. The temporary lead of claim 37, wherein the proximal ends of thefirst and second conductors slide within recesses disposed in the distalends of the first and second connectors, the proximal ends of theconductors being crimped, brazed, soldered, or welded in place thereinto establish electrical and mechanical connections between theconductors and the connectors.
 73. The temporary lead of claim 37,wherein the weakened zone is formed by attaching elastically,frictionally engaging, crimping, gluing, brazing, soldering, or weldingthe proximal ends of the connectors to the distal end of the firstportion of the needle assembly.
 74. A temporary medical lead havingdistal and proximal ends, the lead being suitable for pacing, sensing,monitoring, or defibrillating at least a portion of a human or animalorgan, comprising:(a) a lead body having distal and proximal ends andcomprising at least first and second means for conducting electricity,said first and second conducting means having proximal ends, the firstand second electrical conductors being electrically insulated from oneanother, and at least first and second electrodes attached,respectively, to the first and second conducting means, and (b) asubstantially rigid means for piercing assembly having distal andproximal ends, the piercing means assembly comprising: a first proximalportion comprising proximal and distal ends, the first portion having apointed end disposed at the proximal end thereof, a second distalportion comprising at least first and second means for connecting havingdistal and proximal ends, the distal ends of the connecting meansforming the distal end of the piercing means assembly, the firstproximal portion and the second distal portion being substantiallyrigidly connected to one another, a means for weakening being disposedat least propinguant to the region disposed between the first proximalportion and the second distal portion, the piercing means assembly,prior to the first and second portions thereof being manually separatedfrom one another, forming a single contiguous and substantially rigidassembly, the first means for connecting being attached to the proximalend of the first means for conducting, the second means for connectingbeing attached to the proximal end of the second means forconducting;wherein the connecting means may be separated from the firstproximal portion by the application of a sufficiently large bendingmoment to the weakening means, the connecting means being configured forattachment to an external electrical apparatus.
 75. The temporary leadof claim 74, wherein a strand having proximal and distal ends isattached to the distal end of the lead body.
 76. The temporary lead ofclaim 75, wherein the strand is formed of polypropylene.
 77. Thetemporary lead of claim 75, wherein the strand is a monofilament. 78.The temporary lead of claim 75, wherein the strand includes a coilaffixation member.
 79. The temporary lead of claim 78, wherein the coilaffixation member includes ten right hand wound turns and is crimpinglyaffixed to one of the first and second electrodes.
 80. The temporarylead of claim 76, wherein at least one atraumatic needle is attached tothe distal end of the strand.
 81. The temporary lead of claim 80,wherein the at least one atraumatic needle is curved.
 82. The temporarylead of claim 75, wherein the distal ends of the at least first andsecond conducting means terminate in separate needles.
 83. The temporarylead of claim 75, wherein the first and second conducting means areformed of at least one of helically wound strands of multifilamentstainless steel, twisted strands of multifilament stainless steel,single strands of stainless steel, and strands of electricallyconductive polymeric material.
 84. The temporary lead of claim 75,wherein the at least first and second conducting means are inner andouter coaxial conductors, respectively.
 85. The temporary lead of claim84, wherein a layer of inner insulation separates and electricallyinsulates the first inner conducting means from the second outerconducting means, the inner insulation being formed from a materialselected from the group consisting of fluorinated ethylene propylene(FEP), polytetrafluorethylene (PTFE), co-polymer polytetrafluorethylene,polyethylene, silastic, neoprene, polypropylene and polyurethane. 86.The temporary lead of claim 84, wherein the outer conducting means iscomposed of between about 26 and 40 medical grade stainless steelstrands or filaments wound helically over the layer of inner insulation.87. The temporary lead of claim 84, wherein a layer of outer insulationis disposed over the outer surface of the outer second conducting means,the outer insulation being electrically insulative and formed from amaterial selected from the group consisting of FEP, polyethylene,biocompatible PTFE, polyethylene, silastic, neoprene, polypropylene andpolyurethane.
 88. The temporary lead of claim 84, wherein the innerconducting means is composed of about 19 medical grade twisted, wound,or twisted and wound stainless steel filaments or strands.
 89. Thetemporary lead of claim 85, wherein the outer conducting means iscomposed of between about 26 and 40 medical grade stainless steelstrands or filaments wound helically over the inner insulation.
 90. Thetemporary lead of claim 75, wherein the at least first and secondconducting means are zip cord conductors.
 91. The temporary lead ofclaim 75, wherein the at least first and second electrodes are formed ofmedical grade stainless steel.
 92. The temporary lead of claim 75,wherein the first electrode is a distal electrode, the first conductingmeans forms an inner conducting means, and the first electrode ismechanically and electrically connected by the inner conducting means tothe first means for connecting.
 93. The temporary lead of claim 75,wherein the second electrode is a proximal electrode, the secondconducting means forms an outer conducting means, and the secondelectrode is mechanically and electrically connected by the outerconducting means to the second means for connecting.
 94. The temporarylead of claim 75, wherein the first portion of the piercing meansassembly is a needle.
 95. The temporary lead of claim 94, wherein thefirst portion forms an atraumatic needle.
 96. The temporary lead ofclaim 94, wherein the first portion of the piercing means assembly issubstantially straight.
 97. The temporary lead of claim 94, wherein thefirst portion of the piercing means assembly has a triangularcross-section.
 98. The temporary lead of claim 94, wherein the firstportion of the piercing means assembly is a Keith-type needle.
 99. Thetemporary lead of claim 94, wherein the first portion of the piercingmeans assembly is formed of medical grade plastic or polymer.
 100. Thetemporary lead of claim 94, wherein the first portion of the piercingmeans assembly is curved.
 101. The temporary lead of claim 75, whereinthe distal end of the first portion of the piercing means assembly isattached crimpingly, compressionally, adhesively, gluingly, elastically,frictionally or slidingly to the first and second means for connecting.102. The temporary lead of claim 75, wherein the first and second meansfor connecting, upon being separated from the distal end of the firstportion of the piercing means assembly, form cylindrically-shaped pinconnectors having at least one of circular cross-sections, rectangularcross-sections and square cross-sections.
 103. The temporary lead ofclaim 75, wherein the first and second means for connecting formreed-shaped connectors.
 104. The temporary lead of claim 75, wherein thefirst and second means for connecting form flexible connectors.
 105. Thetemporary lead of claim 75, wherein the first and second means forconnecting each have a reduced diameter pin disposed at its proximalend.
 106. The temporary lead of claim 105, wherein the reduced diameterpins fit into corresponding axial recesses disposed within the distalend of the first portion of the piercing means assembly.
 107. Thetemporary lead of claim 106, wherein the proximal ends of the means forconnecting are frictionally engaged, adhered, glued, crimped, brazed,soldered or welded to the distal end of the first portion of thepiercing means assembly.
 108. The temporary lead of claim 75, whereinthe first and second means for connecting have proximal ends that fitwithin corresponding axial recesses disposed within the distal end ofthe first portion of the piercing means assembly.
 109. The temporarylead of claim 108, wherein the proximal ends of the first and secondmeans for connecting are frictionally engaged, adhered, glued, crimped,brazed, soldered or welded to the distal end of the first portion of thepiercing means assembly.
 110. The temporary lead of claim 75, whereinthe proximal ends of the first and second means for conducting slidewithin recesses disposed in the distal ends of the first and secondmeans for connecting, the means for conducting being crimped, brazed,soldered, or welded in place therein to establish electrical andmechanical connections between the means for conducting and the meansfor connecting.
 111. The temporary lead of claim 75, wherein the meansfor weakening is formed by attaching elastically, frictionally engaging,crimping, gluing, brazing, soldering or welding the proximal ends of themeans for connecting to the distal end of the first portion of thepiercing means assembly.
 112. A temporary medical lead having distal andproximal ends, the lead being suitable for pacing, sensing, monitoring,or defibrillating at least a portion of a human or animal organ,comprising:(a) a lead body having distal and proximal ends andcomprising at least first and second means for conducting electricity,said first and second conducting means having proximal ends, the firstand second electrical conductors being electrically insulated from oneanother, and at least first and second electrodes attached,respectively, to the first and second conducting means, and (b) asubstantially rigid means for piercing assembly having distal andproximal ends, the piercing means assembly comprising: a first proximalportion comprising proximal and distal ends, the first portion having apointed end disposed at the proximal end thereof, a second distalportion comprising at least first and second means for connecting havingdistal and proximal ends, the distal ends of the connecting meansforming the distal end of the piercing means assembly, the firstproximal portion and the second distal portion being substantiallyrigidly connected to one another, a means for weakening being disposedat least propinguant to a region disposed between the first proximalportion and the second distal portion, the piercing means assembly,prior to the first and second portions thereof being manually separatedfrom one another, forming a single contiguous and substantially rigidassembly, the first means for connecting being attached to the proximalend of the first means for conducting, the second means for connectingbeing attached to the proximal end of the second means forconducting;wherein the connecting means may be separated from the firstproximal portion by the application of a sufficiently pulling force tothe weakening means, the connecting means being configured forattachment to an external electrical apparatus.
 113. The temporary leadof claim 112, wherein a strand having proximal and distal ends isattached to the distal end of the lead body.
 114. The temporary lead ofclaim 113, wherein the strand is formed of polypropylene.
 115. Thetemporary lead of claim 113, wherein the strand is a monofilament. 116.The temporary lead of claim 113, wherein the strand includes a coilaffixation member.
 117. The temporary lead of claim 116, wherein thecoil affixation member includes ten right hand wound turns and iscrimpingly affixed to one of the first and second electrodes.
 118. Thetemporary lead of claim 113, wherein at least one atraumatic needle isattached to the distal end of the strand.
 119. The temporary lead ofclaim 118, wherein the at least one atraumatic needle is curved. 120.The temporary lead of claim 112, wherein the distal ends of the at leastfirst and second conducting means terminate in separate needles. 121.The temporary lead of claim 112, wherein the first and second conductingmeans are formed of at least one of helically wound strands ofmultifilament stainless steel, twisted strands of multifilamentstainless steel, single strands of stainless steel, and strands ofelectrically conductive polymeric material.
 122. The temporary lead ofclaim 112, wherein the at least first and second conducting means areinner and outer coaxial conductors, respectively.
 123. The temporarylead of claim 113, wherein a layer of inner insulation separates andelectrically insulates the first inner conducting means from the secondouter conducting means, the inner insulation being formed from amaterial selected from the group consisting of fluorinated ethylenepropylene (FEP), polytetrafluorethylene (PTFE), co-polymerpolytetrafluorethylene, polyethylene, silastic, neoprene, polypropyleneand polyurethane.
 124. The temporary lead of claim 123, wherein theouter conducting means is composed of between about 26 and 40 medicalgrade stainless steel strands or filaments wound helically over thelayer of inner insulation.
 125. The temporary lead of claim 122, whereina layer of outer insulation is disposed over the outer surface of theouter second conducting means, the outer insulation being electricallyinsulative and formed from a material selected from the group consistingof FEP, polyethylene, biocompatible PTFE, polyethylene, silastic,neoprene, polypropylene and polyurethane.
 126. The temporary lead ofclaim 122, wherein the inner conducting means is composed of about 19medical grade twisted, wound, or twisted and wound stainless steelfilaments or strands.
 127. The temporary lead of claim 123, wherein theouter conducting means is composed of between about 26 and 40 medicalgrade stainless steel strands or filaments wound helically over theinner insulation.
 128. The temporary lead of claim 112, wherein the atleast first and second conducting means are zip cord conductors. 129.The temporary lead of claim 112, wherein the at least first and secondelectrodes are formed of medical grade stainless steel.
 130. Thetemporary lead of claim 112, wherein the first electrode is a distalelectrode, the first conducting means forms an inner conducting means,and the first electrode is mechanically and electrically connected bythe inner conducting means to the first means for connecting.
 131. Thetemporary lead of claim 112, wherein the second electrode is a proximalelectrode, the second conducting means forms an outer conducting means,and the second electrode is mechanically and electrically connected bythe outer conducting means to the second means for connecting.
 132. Thetemporary lead of claim 112, wherein the first portion of the piercingmeans assembly is a needle.
 133. The temporary lead of claim 132,wherein the needle is atraumatic.
 134. The temporary lead of claim 132,wherein the needle is substantially straight.
 135. The temporary lead ofclaim 132, wherein the needle has a triangular cross-section.
 136. Thetemporary lead of claim 132, wherein the needle is a Keith-type needle.137. The temporary lead of claim 132, wherein the needle is formed ofmedical grade plastic or polymer.
 138. The temporary lead of claim 132,wherein the needle is curved.
 139. The temporary lead of claim 112,wherein the distal end of the first portion of the piercing meansassembly is attached crimpingly, compressionally, adhesively, gluingly,elastically, frictionally or slidingly to the proximal ends of the firstand second means for connecting.
 140. The temporary lead of claim 112,wherein the first and second means for connecting, upon being separatedfrom the distal end of the first portion of the piercing means assembly,form cylindrically-shaped pin connectors having at least one of circularcross-sections, rectangular cross-sections and square cross-sections.141. The temporary lead of claim 112, wherein the first and second meansfor connecting form reed-shaped connectors.
 142. The temporary lead ofclaim 112, wherein the first and second means for connecting formflexible connectors.
 143. A method for implanting a temporary medicallead having distal and proximal ends, the lead being suitable forpacing, sensing, monitoring, or defibrillating at least a portion of ahuman or animal organ, the lead comprising: (1) a lead body havingdistal and proximal ends and comprising at least first and secondelectrical conductors having proximal ends, the first and secondelectrical conductors being electrically insulated from one another, andat least first and second electrodes attached, respectively, to thefirst and second electrical conductors, and (2) a substantially rigidneedle assembly having distal and proximal ends, the needle assemblycomprising a first proximal portion comprising proximal and distal ends,the first portion having a pointed end disposed at the proximal endthereof, a second distal portion comprising at least first and secondconnectors having distal and proximal ends, the distal ends of theconnectors forming the distal end of the needle assembly, the firstproximal portion and the second distal portion being substantiallyrigidly connected to one another, a weakened zone being disposed atleast propinquant to a region disposed between the first proximalportion and the second distal portion, the needle assembly, prior to thefirst and second portions thereof being manually separated from oneanother, forming a single contiguous and substantially rigid assembly,the first connector being attached to the proximal end of the firstelectrical conductor, the second connector being attached to theproximal end of the second electrical conductor, wherein the connectorsmay be separated from the first proximal portion by the application of asingle sufficiently large bending moment or pulling force to theweakened zone, the connectors being configured for attachment to anexternal electrical apparatus, the method comprising the steps of:(a)positioning the at least two electrodes in electrical contact with theportion of the organ; (b) securing the electrodes to the portion of theorgan, and (c) separating the connectors from the first portion of theneedle assembly by the application of a sufficiently large bendingmoment or pulling force to the weakened zone.
 144. The method of claim143, wherein the positioning step is preceded by a first piercing step,the first piercing step comprising the step of piercing the organ with apointed end of a curved needle, the curved needle being attached to thedistal end of the lead.
 145. The method of claim 143, wherein a secondpiercing step precedes the separating step, the second piercing stepcomprising the step of piercing the thorax of a patient with a pointedend of the chest needle, the pointed end being disposed at the proximalend of the chest needle.
 146. The method of claim 143, wherein aconnecting step follows the separating step, the connecting stepcomprising the step of electrically connecting the connectors to anexternal electrical apparatus.
 147. A method for making a temporarymedical lead having distal and proximal ends, the lead being suitablefor pacing, sensing, monitoring, or defibrillating at least a portion ofa human or animal organ, the lead comprising: (1) a lead body havingdistal and proximal ends and comprising at least first and secondelectrical conductors having proximal ends, the first and secondelectrical conductors being electrically insulated from one another, andat least first and second electrodes attached, respectively, to thefirst and second electrical conductors, and (2) a substantially rigidneedle assembly having distal and proximal ends, the needle assemblycomprising a first proximal portion comprising proximal and distal ends,the first portion having a pointed end disposed at the proximal endthereof, a second distal portion comprising at least first and secondconnectors having distal and proximal ends, the distal ends of theconnectors forming the distal end of the needle assembly, the firstproximal portion and the second distal portion being substantiallyrigidly connected to one another, a weakened zone being disposed atleast propinquant to a region disposed between the first proximalportion and the second distal portion, the needle assembly, prior to thefirst and second portions thereof being manually separated from oneanother, forming a single contiguous and substantially rigid assembly,the first connector being attached to the proximal end of the firstelectrical conductor, the second connector being attached to theproximal end of the second electrical conductor, wherein the connectorsmay be separated from the first proximal portion by the application of asingle sufficiently large bending moment or pulling force to theweakened zone, the connectors being configured for attachment to anexternal electrical apparatus, the method comprising the steps of:(a)providing the lead body; (b) providing the at least first and secondelectrodes; (c) providing the needle assembly; (d) attaching the distalends of the first and second connectors to the proximal ends of thefirst and second electrical conductors, respectively; (e) attaching theproximal ends of the first and second connectors to the distal end ofthe first portion of the needle assembly, and (f) providing the weakenedzone.
 148. A temporary medical lead having distal and proximal ends, thelead being suitable for pacing, sensing, monitoring, or defibrillatingat least a portion of a human or animal organ, comprising:(a) a leadbody having distal and proximal ends and comprising at least first andsecond electrical conductors having proximal ends, the first and secondelectrical conductors being electrically insulated from one another, andat least first and second electrodes attached, respectively, to thefirst and second electrical conductors; (b) a needle having distal andproximal ends, the needle having a blunt end disposed at its distal end;(c) at least first and second connectors having proximal and distalends, the first connector being attached to the proximal end of thefirst electrical conductor, the second connector being attached to theproximal end of the second electrical conductor, the first and secondconnectors having reduced diameter pins disposed at the proximal endsthereof, the reduced diameter pins fitting into corresponding individualrecesses disposed within the blunt end, the reduced diameter pins beingfrictionally engaged, adhered, glued, crimped, brazed, soldered orwelded to the blunt end, each of the first and second connectors havinga scored region disposed between the reduced diameter pin and theproximal end thereof, the scored region forming a weakened zone, and (d)a weakened zone disposed between the first and second electricalconnectors and the blunt end;wherein the connectors may be separatedfrom the blunt end by application of a sufficiently large bending momentto the weakened zone, the connectors being configured for attachment toan external electrical apparatus.
 149. A temporary medical lead havingdistal and proximal ends, the lead being suitable for pacing, sensing,monitoring, or defibrillating at least a portion of a human or animalorgan, comprising:(a) a lead body having distal and proximal ends andcomprising at least first and second electrical conductors havingproximal ends, the first and second electrical conductors beingelectrically insulated from one another, and at least first and secondelectrodes attached, respectively, to the first and second electricalconductors; (b) a needle having distal and proximal ends, the needlehaving a blunt end disposed at its distal end; (c) at least first andsecond connectors, the first connector being attached to the proximalend of the first electrical conductor, the second connector beingattached to the proximal end of the second electrical conductor, and (d)a weakened zone disposed between the first and second electricalconnectors and the blunt end;wherein the connectors may be separatedfrom the blunt end by application of a sufficiently large pulling forceto the weakened zone, the connectors being configured for attachment toan external electrical apparatus, the proximal ends of the first andsecond conductors sliding within corresponding recesses disposed in thedistal ends of the first and second connectors, the proximal ends of theconductors being crimped, brazed, soldered, or welded in place thereinto establish electrical and mechanical connections between theconductors and the connectors, the weakened zone being formed byattaching elastically, frictionally engaging, crimping, gluing, brazing,soldering, or welding the proximal ends of the connectors to the bluntend of the needle.